Certain printing machines receive marking material in a form known as an ink stick. The ink stick is a solid or semi-solid structure formed from the marking material, wherein the structure is wholly or partially consumed in the printing process. Unlike powdered or liquid marking materials, ink sticks can be handled and installed without a bottle, cartridge, or other container. Ink sticks may be of any convenient shape (e.g., a pellet, block, brick, cube, or any other geometric structure) for handling and loading into the printing apparatus.
For example, one printing apparatus that uses ink sticks is known as a phase change or solid ink printer. In phase change printers, a feed mechanism delivers the ink stick to a heater assembly, where the ink is melted into a liquid state for depositing onto a receiving medium. U.S. Pat. No. 5,734,402 for an “Ink Feed System”, issued Mar. 31, 1998 to Rousseau et al.; and U.S. Pat. No. 5,861,903 for an “Ink Feed System”, issued Jan. 19, 1999 to Crawford et al., which are incorporated by reference herein in their entirety, describe exemplary systems for delivering ink sticks into a phase change printer.
Ink sticks hold their shape and, therefore, may be handled and loaded into the printing apparatus without the need for a container or cartridge, as is typically required for liquid ink or powdered toner. Furthermore, the entire ink stick may be melted and consumed, with no need to dispose of, or recycle, any container. Eliminating the need for a container provides many advantages to the use of ink sticks. However, without the use of a container, there are no mechanisms for authenticating or otherwise identifying the ink stick.
A common trend in the office equipment industry is to provide expendable supply units (e.g., copier and printer toner bottles, cartridges, and the like), also known as customer replaceable units (CRUs) or modules, with electronically-readable memory devices, also known as customer replaceable unit monitors (CRUMs), which, when the module is installed in the machine, enable the machine to both read information from the CRUM and also write information to the CRUM. The information read from, or written to, the CRUM may be used by the machine to perform various functions, such as verifying the authenticity of the module, providing operational set points to the machine, and others. For example, U.S. Pat. No. 6,016,409 entitled “System For Managing User Modules in a Digital Printing Apparatus”, which is incorporated by reference herein in its entirety, describes various data that may be stored in a CRUM and various functions that may be performed using this data.